Since mobile devices are getting smaller in size, and semiconductor devices used for such mobile devices are required to be smaller in size as well. In order to achieve such a request, a semiconductor device called “chip size package”, having a dimension corresponding to a semiconductor chip, has been developed. Chip size package includes a Wafer Level Chip Size Package and a Wafer Level Chip Scale Package (WCSP). A front or top surface of a semiconductor chip (semiconductor substrate) is sealed with a resin, while a rear or bottom surface, which is a silicon surface, is exposed.
A WCSP is mounted on a mount board so that a front surface of the semiconductor chip faces the mount board. In other words, a WCSP is mounted on a mount board so that a rear or bottom surface faces upward, as shown in Japanese Patent Publication No. 2003-60120A.
However, according to a WCSP described in the above publication, a rear surface of a semiconductor chip is exposed, so that an edge chipping may be occurred at an edge of the semiconductor chip when an external force is applied thereto. The edge of the semiconductor chip may be broken. When a broken piece caused by an edge chipping phenomenon is stuck on to a mount board, short-circuit would be made. Now, it has been required to prevent such an edge chipping phenomenon from a WCSP.